This invention relates in general to a bondable orthodontic appliance, and more particularly to an appliance bondable to a tooth with a light-cure adhesive, and still more particularly to a bondable orthodontic appliance for the posterior teeth having a light-cure adhesive bonding face bondable to a tooth by a light-cure adhesive.
Orthodontic treatment of a patient usually begins with the placement of fixed appliances, which includes molar tubes at the distal ends of the arches for receiving and anchoring distal ends of archwires. Such tubes are usually mounted with bands. Mounting tubes by bonding is becoming more popular.
Heretofore, it has been well known to bond appliances to teeth with lightcure adhesives, and that the advantage of directly bonding appliances to teeth permits a lower profile, thereby eliminating the need for offset bends in archwire. While it is known to bond molar tubes to molar teeth at the posterior of the mouth, it is also known that molar tubes require higher bond strengths because they are subjected to greater forces from the archwire during orthodontic treatment.
It is also known that bonding with light-cure adhesives requires good access to the bond site in order to allow the light source to properly penetrate and adequately cure the adhesive. Good access is not generally possible when mounting current bondable appliances to molar teeth. Inadequate curing of a light-cure adhesive results in premature separation of the appliance from a tooth, requiring rebonding during the treatment of a patient, which is not only time-consuming to the orthodontic practitioner but can adversely affect the treatment time when rebonding may be delayed.
When bonding an appliance to a tooth with a light-cure adhesive, one of the problems encountered in bonding molar appliances is in obtaining a satisfactory cure of the adhesive. Molars are far back in the mouth at the posterior of the arch, and while a curing light can easily direct light to the mesial and occlusal edges of a bonding pad, it is not possible to direct the light at the distal and gingival edges of the pad. Therefore, when mounting an appliance on a tooth, because adhesive must fill the spaces on the bonding face of an appliance which are not accessible to a light source at the mesial and distal edges of an appliance, incomplete curing results in producing an unreliable bond for maintaining the appliance in place throughout orthodontic treatment.
The present invention solves the bonding strength problem by providing a bondable appliance that enhances the curing of the light-cure adhesive at bonding sites deeper in the oral cavity in the posterior of the arches.
Bondable appliances include a bonding pad that is either integrally formed with the appliance by casting so it is one piece or is attachable to the appliance by a suitable method. For example, it is well known to provide mesh bonding pads consisting of a metal foil and mesh attached to the foil such as closed in U.S. Pat. No. 4,068,379. Such a mesh bonding pad is securable to an appliance such as by welding.
It is also well known, as shown in the above identified patent, to provide one-piece appliances that have a bonding pad integrally formed with the appliance and with a textured bonding face for receiving a bondable adhesive and for attachment to a tooth.
It is also known to cure light-cure adhesive in a bonding process by using a light-curing unit or a plasma arc light-curing unit, the latter of which significantly reduces the light-curing time over the conventional light-curing unit.
The present invention enhances the bond strength when bonding an appliance to a tooth by precoating the bondable surface of the appliance with a light-cure adhesive prior to bonding the appliance to a tooth with light-cure adhesive. More specifically, the heretofore encountered problem of incomplete curing of a light-cure adhesive when bonding a molar appliance is solved by applying a light-cure adhesive over the bonding pad of an appliance and then curing that adhesive when it can be fully subjected to a curing light at the factory. Thereafter, when the adhesive-filled pad of the appliance is to be mounted on a molar tooth, the entire light-curable adhesive added between the pad and tooth will be more accessible to a light-curing operation because the layer of adhesive provided between the cured adhesive surface of the molar pad and the tooth can be more fully subjected to the light-curing energy. Accordingly, a more reliable bond is obtained to enhance the bond strength.
The present invention also involves the steps of making the appliance with its light-cure adhesive pad prior to the application of the light-cure adhesive to the pad of the appliance during mounting of the appliance on a tooth so as to assure a strong bond between the adhesive and the bonding pad of the appliance.
Preparing the bondable appliance first requires thoroughly cleaning the appliance with a plasma cleaning machine. The bonding pad is then treated with silane and prime coated with a thin layer of modified acrylic copolymer. The silane is cured before the application of the prime coat. After curing the prime coat, the pad is filled with a light-cure adhesive that is light cured. Thereafter, the surface of the adhesive is mechanically etched or sandblasted to create a rough surface for enhancing the bonding with adhesive when bonding the appliance on a tooth.
The strength of a bond for an appliance according to the present invention is about 25% greater than the strength of a bond of prior known appliances.
It is therefore an object of the present invention to provide a new and improved bondable orthodontic appliance bondable with a light-cure adhesive to a tooth.
It is a further object of the present invention to provide a bondable orthodontic appliance particularly for a bond site deep in the oral cavity having enhanced bond strength wherein the bonding base or pad of the appliance is precoated with a light-cured adhesive that is cured and surface roughened.
A further object of the present invention is in the provision of a method of making a bonding base on an orthodontic appliance with a light-cure bonding material face including the steps of cleaning the appliance and bonding base, applying a coating of silane to the base, heat-curing the silane, applying a coating of acrylic copolymer to the base, and covering the base with a light-curable adhesive, and light-curing the adhesive.
Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts.